The overall objectives of this research are to acquire an understanding of the normal pattern of development in human fetal brain, and a detailed knowledge of some of the mechanisms whereby disordered fetal development occurs. Specimens are obtained from hysterotomies, which are performed for the purpose of terminating pregnancies. Studies are made on cultures established from various parts of the brain, and on fixed tissue blocks. Goals for the forthcoming year are to investigate ultrastructural aspects of radial glia and the onset of glial fibrillary acidic protein synthesis in the cerebellum; immunohistochemical localization of glial fibrillary acidic protein at the ultrastructural level; utilizing bromoxyuridine followed by exposure to ultraviolet light, to attempt to produce cultures of neurons free of astrocytes; study the vulnerability of neurons and astrocytes in culture to x-irradiation; analyze the development and differentiation of ependymal cells; utilizing spinal cord, study the early stages of oligodendroglial development and differentiation, and early stages of myelin formation. BIBLIOGRAPHIC REFERENCES: Interactions of neurons and astrocytes during growth and development of human fetal brain in vitro, by B.H. Choi and L.W. Lapham. Exper. and Mol. Pathol., 24: 110-125, 1976. The demonstration of glial fibrillary acidic protein in the cerebrum of the human fetus by indirect immunofluorescence, by D.S. Antanitus, B.H. Choi, and L.W. Lapham. Brain Res., 103: 613-616, 1976.